Drill string system for performing measurement while drilling and logging while drilling operations

ABSTRACT

A drill string system for performing measurement while drilling and logging while drilling operations for oil and gas drilling is provided. The drill string system includes a drill string section having a bore defined by an inner length of surface of a pipe wall which has an outer surface. A tool guide is secured in the drill string section and a support is provided for centering the tool guide in said bore. Communication ports extend through the drill pipe wall from the outer pipe surface to the inner surface and through the support to an inner surface of the tool guide, said communication ports being in communication with one another. An elongate cylindrical tool is disposed in the tool guide. A first terminated passageway in the tool is in communication with a pressure sensor within the tool to sense the drill string annular pressure. A second terminated passageway in the tool is in communication with the drill string bore and in communication with a pressure sensor within the tool to sense the drill string bore pressure. A three-dimensional orientation sensor in the tool determines orientation of the tool. An alignment mechanism is provided by the tool and the tool guide to inhibit rotation of the tool relative to the tool guide when the tool is in a desired orientation relative to the tool guide. The first terminated passageway is in communication with the communication port of the tool guide when the tool is in the desired orientation.

FIELD OF THE INVENTION

The invention relates generally to the field of drilling and, more particularly, to the field of“underbalanced” drilling systems.

BACKGROUND OF THE INVENTION

Petroleum exploration activities occasionally require specialized drilling techniques to optimise production from certain types of reservoir stratum. One such drilling technique is known as “underbalanced” drilling, which employs singly or a combination of nitrogen, carbon dioxide or other inert gasses, and drilling mud as the primary composite drilling fluid. In this situation, downhole pressure of the composite drilling fluid is monitored within the drill string bore and the well annulus, with the goal of preventing formation fracture due to overly high gas pressures. Another goal of underbalanced drilling is to minimise loss of the composite drilling fluid to the formation, which can be re-circulated until drilling is complete. As with all directional drilling, the orientation of the drill string is monitored to determine the actual drilling path to permit correction where the actual drilling path has deviated from the desired drilling path.

Such systems generally employ a tool disposed in the bore of the drill string that is operable to both determine the pressure inside and outside and the orientation of the drill string. The tool includes a three-dimensional orientation sensor for determining the orientation of the tool. As it is ultimately desired to determine the orientation of the drill string, the tool is secured in a fixed known position inside the drill string. The orientation of the drill string can thereafter be determined using the orientation information reported by the tool to the surface. In current systems, the orientation of the tool relative to the drill string is maintained by retaining the tool in a tool guide at its upper end and seating the tool in a mule shoe at its lower end. The tool guide permits rotation and vertical travel of the tool. The mule shoe has a helical groove into which the tool is fitted in order to limit vertical travel of the tool and to maintain the tool in a known orientation relative to the drill string. Deployment of the muleshoe, however, is time-consuming and costly.

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, there is provided a drill string system for performing measurement while drilling and logging while drilling operations for oil and gas drilling, said drill string system comprising:

a drill string section having a bore defined by an inner length of surface of a pipe wall which also has an outer surface;

a tool guide secured in said drill string section and a support for centering said tool guide in said bore;

communication ports extending through said drill pipe wall from said outer pipe surface to said inner surface and through said support to an inner surface of said tool guide, said communication ports being in communication with one another;

an elongate cylindrical tool disposed in said tool guide;

a first terminated passageway in said tool in communication with a pressure sensor within said tool to sense said drill string annular pressure;

a second terminated passageway in said tool in communication with said drill string bore and in communication with a pressure sensor within said tool to sense said drill string bore pressure;

a three-dimensional orientation sensor in said tool determining orientation of the tool; and

an alignment mechanism provided by said tool and said tool guide for inhibiting rotation of said tool relative to the tool guide when said tool is in a desired orientation relative to said tool guide, said first terminated passageway being in communication with said communication port of said tool guide when said tool is in said desired orientation.

The alignment mechanism can be an alignment key and a corresponding key slot. The alignment key and key slot can extend longitudinally along the tool guide and the tool. The alignment key can be at least one biasable element and the alignment key can be tapered at a lower longitudinal end thereof. The key slot can also be tapered at a lower longitudinal end thereof. The support can be a fit ring connected to the tool guide via support legs extending longitudinally along the tool guide, the fit ring being fitted to the inner diameter of the drill string pipe. The drill string system can include ring seals above and below the communication port on the tool guide.

The tool can comprise at least one spacer at a lower end thereof for spacing the tool from the drill string pipe. The at least one spacer can be centralizer fins that extend generally radially from the tool. The tool can include a feature to abut against the tool guide to limit vertical movement of the tool in the drill string pipe. The tool guide can be tubular.

In accordance with another aspect of the invention, there is provided a drill string system for performing measurement while drilling and logging while drilling operations for oil and gas drilling, said drill string system comprising:

a drill string section having a bore defined by an inner length of surface of a pipe wall which also has an outer surface;

a tool guide secured in said drill string section and a support for centering said tool guide in said bore;

communication ports extending through said drill pipe wall from said outer pipe surface to said inner surface and through said support to an inner surface of said tool guide, said communication ports being in communication with one another;

an elongate cylindrical tool disposed in said tool guide;

a first pressure sensor within said tool to sense said drill string annular pressure;

a second pressure sensor in said tool in communication with said drill string bore to sense said drill string bore pressure;

a three-dimensional orientation sensor in said tool determining orientation of the tool; and

a mechanical retention device connected to said tool guide for inhibiting rotation of said tool relative to the tool guide when said tool is in a desired orientation relative to said tool guide, said first terminated passageway being in communication with said communication port of said tool guide when said tool is in said desired orientation.

In accordance with a further aspect of the invention, there is provided a landing assembly for use in a drill string section, said landing sleeve assembly comprising:

a tool guide for receiving an elongate cylindrical tool;

a support for centering said tool guide in a bore of said drill string section;

a communication port extending through said tool guide and said support for communication with a corresponding communication port in said drill string section and a pressure sensor in said tool when said landing assembly is placed in said drill string section; and

a mechanical retention device connected to said tool guide and said support for inhibiting rotation of said tool relative to the tool guide when said tool is in a desired orientation relative to said tool guide.

The drill string system and landing assembly of the invention facilitates and/or maintains correct rotational alignment of a pressure measurement and orientation tool within a drill string bore.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described with respect to the drawings wherein:

FIG. 1 is a schematic diagram of a downhole drill string;

FIG. 2 a is a sectional view of the lower end of the drill string;

FIG. 2 b is a schematic diagram of the geometry of the drill string;

FIG. 3 is a sectional view of a drill string system of this invention;

FIG. 4 is an exploded sectional view of the drill string system of FIG. 3;

FIG. 5 is another exploded view of the drill string system of FIG. 3; and

FIG. 6 is a sectional view of a drill string section with a landing shoe assembly placed therein.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A representative drilling system is shown in FIGS. 1 and 2 a. The above ground drilling structure 10 has the usual tower 11 with drill string assembly and drive components 12. The drill string 13 is made up of individual drill string sections 14. The lowest drill string section is coupled to a collar 15, a bent subassembly 16, and a mud motor in unit 17 for driving a drill bit 18. The drilling structure 10 operates in a bore 19 in the earth formation created by the downward movement of the drill bit 18. The space around the drill string 13 within the bore 19 is referred to as an annular space 20. The drilling structure is capable of performing directional drilling via the drill bit 18 that is angled via the bent subassembly 16.

FIG. 2 b illustrates various axes corresponding to the orientation of the drill string system. The vector representing the axis of the lower end of the drill string 13 is identified as A_(DS). The vector representing the axis of the drill bit is identified as A_(DB). The vector A_(DB) has a component that is coaxial to A_(DS), namely A_(DB) ^(C), and a component that is normal to A_(DS), namely A_(DB) ^(N). A vector, V_(HS), is defined as being the polar opposite of A_(DB) ^(N). This vector represents the “highside” of the drill string 13 as indicated on FIG. 2 a. In order to cause the drill bit 18 to “steer” away from the highside direction, downward pressure is applied to the drill string 13, causing the drill bit 18 to deviate direction.

In order to clear away materials from the drill bore 19, a drilling fluid is pumped downwards through a bore in the drill string 13. The drilling fluid exits the drill string 13 adjacent the drill bit 18 and flows upwards within the annular space 20 about the periphery of the drill string 13. Differences between the drill string bore pressure and drill string annular pressure can result in fractures in the drill string 13. In order to monitor these pressures, the drill string 13 is provided with electronic components that are used to provide for “measurement while drilling and logging while drilling operations”.

A drill string system 24 in accordance with an embodiment of the invention shown in FIG. 3. The system 24 enables alignment of the electronic components in a fixed orientation within a specialized downhole drill string segment referred to as a landing sleeve 28. An upper female connector 32 of the landing sleeve 28 is connected to a male threaded connector of an upper drill string section. Correspondingly, a lower male connector 36 of the landing sleeve 28 is threaded into the collar 15. The electronic components for measurement while drilling, logging while drilling and the determination of orientation are housed in an elongate cylindrical tool 40. The tool 40 is positioned within a landing shoe assembly 44 that is fitted within the landing sleeve 28. A tapered sleeve insert 48 is disposed above the landing shoe assembly 44 in the landing sleeve 28 and a seal ring 52 is placed atop the tapered sleeve insert 48. Centralizer fins 56 project generally radially from a lower end 60 of the tool 40 to fix the lower end 60 of the tool 40 in a coaxial relation within the landing sleeve 28. The centralizer fins 56 permit flow of drill fluid thereby. A toothed crown 64 is secured to an upper end of the tool 40 and allows a rotational force to be applied to the tool 40 in order to rotate it when it is disposed within the landing sleeve 28.

The cylindrical tool 40 contains a multitude of electrical opponents therein, including devices for measuring drilling fluid pressure in a bore 68 of the drill string and the drill string annular pressure in the annular space 20. The annular space 20 is defined between earth formations and an exterior 76 of the landing sleeve 28. A pressure transducer 80 is provided to measure the pressure of a circulating drilling fluid in the drill string bore 68. A port 104 in the tool 40 communicates with a passageway 108, and terminates at the pressure transducer 80. The pressure in the annular space 20 surrounding the drill string is measured by a pressure transducer 92. The pressure transducer 92 is in communication with a passageway 96 which, in turn, communicates through a port 100. In turn, port 100 is in communication with a port 104 through the landing shoe assembly 44 and ultimately with a passageway 108 in the landing sleeve 28. The external entrance of the port 104 is located within a recessed region 106 on the periphery of the landing shoe assembly 44. The passageway 108 has a removable plug 112 inserted therein that fits into the recessed region 106 of the landing shoe assembly 44 to fix movement of the landing shoe assembly 44 relative to the landing sleeve 28. The removable plug 112 has a port 116 that communicates with the annular space 20, noted as the drill string annular space 20 that conveys returned drilling fluid to the surface. As a result, the pressurized fluid in the annular space 20 outside of the landing sleeve 28 can communicate static pressure through ports 116, 104 and 100 and through passageway 96 to the pressure transducer 92.

Port 104 is located on a side of the tool 40 opposite port 100 and is in communication with the pressurized fluid within the bore of the drill string. Port 100 is located between seals generally designated as 120 and 124. The cylindrical tool 40 is of a dimension that readily slides through the bore of landing shoe assembly 44. Seals 120 and 124 project slightly from the periphery of the tool and form an interference fit with the interior surface 128 of the landing shoe assembly 44, the resulting seal deformation providing a liquid tight seal with the interior of the landing shoe assembly 44. As a result, the seals 120 and 124 prevent the fluid from the drill string bore 68, which is at a higher pressure than the fluid in the annular space 20, from leaking into the annular space formed between the seals 120 and 124, the tool 40 and landing shoe assembly 44.

A third seal 132 similar to seals 120, 124 is provided to stabilize lateral movement of the tool 40 within the landing shoe assembly 44. Although, in accordance with this embodiment, the seals are provided in the tool 40, it is appreciated that the seals may be provided on the inner surface 128 of the landing shoe assembly 44 to provide a sealed space when the tool 40 is inserted into the landing shoe assembly 44.

The landing shoe assembly 44 includes an outer fit ring 136 attached to an upper end of a tool guide 140 by three legs 144. The tool guide 140 can be any shape that permits axial and rotational movement of the tool 40 while retaining the tool coaxially relative to the landing sleeve 28. The outer fit ring 136 and the tool guide 140 are coaxially aligned. The legs 144 radially extend from the tool guide 140 to the outer fit ring 136 to space the outer periphery of the tool guide 140 from the interior surface of the landing sleeve 28. Three arcuate channels 152 are defined by the legs 144 between the outer fit ring 136 and the tool guide 140. The arcuate channels 152 allow the pressurized drilling fluid in the drill string bore 68 to flow through the spaces defined between the periphery of the tool guide 140 and the interior of the landing sleeve 28. Seals 156, 160 are seal rings that project slightly from the outer periphery of landing shoe assembly. Seals 156, 160 are seal rings that project slightly from the outer periphery of the landing shoe assembly 44.

The tool 40 also includes a three-dimensional orientation sensor 162 for determining its orientation. Various types of three-dimensional orientation sensor known to those skilled in the art can be employed. In the described embodiment, the three-dimensional orientation sensor is a three-dimensional compass.

In order to determine the direction of the drilling being performed, the orientation of the lower end of the drill string is used to gauge along what path the drilling is headed. In particular, the orientation of the landing sleeve 28 is used. As the orientation of the tool 40 can be determined, the tool 40 is fixed in a known orientation inside the landing sleeve 28. This is achieved primarily by an alignment mechanism provided by the tool 40 and the tool guide 140.

The electrical components of the tool 40 communicate the drill string bore and annulus pressures and orientation to the surface via telemetry, such as Mud Pulse Telemetry or Electro-Magnetic Telemetry.

The alignment mechanism includes an alignment key 164 located on a lower end of the tool guide 140. The alignment key 164 is slip-fitted into a vertically-extending machined aperture 168 in an extension of one of legs 144 along the lower end of the tool guide 140. A pair of bolts 170 secures the alignment key 164 to the tool guide 140. The alignment key 164 includes alignment elements 172 that are spring-biased towards the axis of the tool guide 140. The alignment elements 172 form a projection 176 that is tapered at its longitudinal ends.

In addition, the alignment mechanism includes a vertical key slot 180 machined into the outer surface of the tool 40 directly below and radially aligned with the port 100. The key slot 180 has dimensions that are complementary to the projection 176 of the alignment key 164. In particular, the key slot 180 has a tapered upper end 184, that transitions to a flat recess 188 and a tapered lower end 192, providing a valley-like vertical profile. Lateral sides 196, 200 of the key slot 180 are not tapered.

A shoulder 204 of the tool above seal 120 is set in a machined annular recess 208 on the inner surface 128 of the tool guide 44.

The exterior passageway 108 extends through the wall of the landing sleeve 28. The passageway 108 communicates with the port 104 which extends through the leg 144 of the landing shoe assembly 44 via a space defined between the exterior surface of the inner surface 148 of the landing sleeve 28 and the outer surface of the outer fit ring 136 of the landing shoe assembly 44. There is a slight gap between the inner surface 148 of the landing sleeve 28 and the outer surface of the landing shoe assembly 44 to permit insertion of the landing shoe assembly 44 in the landing sleeve 28. This space is sealed off to each side of the port 100 by seals 156 and 160, which form a liquid tight seal with the inner surface 148 of the landing sleeve 28 to inhibit fluid from the bore 68 of the landing sleeve 28 from entering port 104 or passageway 108. This ensures that all pressurized fluids passing through passageway 108 and port 104 are contained within the annular space. The port 104 opens up into the space defined between the exterior surface of the cylindrical tool 40 and the inner surface 128 of the landing shoe assembly 44. There is a slight gap between the cylindrical tool 40 and the inner surface 128 of the landing shoe assembly 44 to permit insertion and retraction of the cylindrical tool 40. This space is sealed off to each side of the port 104 by seals 120 and 124. This ensures that all pressurized fluids passing through passageway 108 and port 104 are contained within the annular space. Port 100 is in communication with the annular space so that any pressurized fluid in the annular space enters port 100 and travels along passage 96. As a result, the pressure of such fluid is sensed by the pressure transducer 92.

When the drilling system 24 is being assembled at the surface, the landing shoe assembly 44 is fitted into the landing sleeve 28. The recessed region 106 is aligned with the passageway 108 and the plug 112 is inserted into the passageway 108. When fully inserted, the plug 112 projects into the recessed region 106 which is dimensioned to inhibit movement of the landing sleeve assembly 44 when the plug 112 is inserted. The tapered sleeve insert 48 is inserted into the landing sleeve 28 after insertion of the landing shoe assembly 44, and the seal ring 52 is placed atop the tapered sleeve insert 48. The tool 40 is then inserted into the bore of the landing sleeve 28 through the landing shoe assembly 44 until the shoulder 204 of the tool 40 abuts against the machined annular recess 208 of the landing shoe assembly 44. The shape of the tapered sleeve insert 48 guides insertion of the cylindrical tool 40 into the landing shoe assembly 44 during assembly.

The tapered sleeve insert 48 and seal ring 52 are retained in place by connection of a drill string section to landing sleeve 28. The seal ring 52 is compressed between the tapered sleeve insert 48 and the end of the male connector 36 of the connecting drill string section, thereby creating a liquid tight seal between the bore of the landing sleeve 28 and that of the connecting drill string section. An apertured bracket is secured over the toothed crown and limits upward movement of the tool 40.

In order to fix the orientation of the tool 40 within the landing sleeve 28, the tool 40 is rotated via a rotary drive coupled to the toothed crown 64 until the alignment key 164 is radially aligned with the key slot 180 of the tool 40. In this position, the projection 176 then moves freely into the key slot 180. Upon biasing of the projection 176 of the alignment key 164 into the key slot 180, abutment of the projection 176 with the side walls 196, 200 inhibits further rotation of the tool 40 in either direction. As the tool guide 140 and the centralizer fins 56 maintain the upper and lower ends of the tool 40 coaxial to the landing sleeve 28, and the alignment mechanism inhibits rotation of the tool 40, the tool 40 is held in a fixed known orientation relative to the landing sleeve 28. Thus, the orientation of the landing sleeve 28 can be determined from the orientation of the tool 40.

Thereafter, further sections of the drill string 13 are appended atop the landing sleeve 28 to construct the drill string 13.

In this manner a reliable economical system is provided which permits securement of a tool having a three-dimensional orientation sensor inside the drill string in a fixed known orientation relative thereto.

Although preferred embodiments of the invention have been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims. 

1. A drill string system for performing measurement while drilling and logging while drilling operations for oil and gas drilling, said drill string system comprising: a drill string section having a bore defined by an inner length of surface of a pipe wall which also has an outer surface; a tool guide secured in said drill string section and a support for centering said tool guide in said bore; communication ports extending through said drill pipe wall from said outer pipe surface to said inner surface and through said support to an inner surface of said tool guide, said communication ports being in communication with one another; an elongate cylindrical tool disposed in said tool guide; a first terminated passageway in said tool in communication with a pressure sensor within said tool to sense said drill string annular pressure; a second terminated passageway in said tool in communication with said drill string bore and in communication with a pressure sensor within said tool to sense said drill string bore pressure; a three-dimensional orientation sensor in said tool determining orientation of the tool; and an alignment mechanism provided by said tool and said tool guide for inhibiting rotation of said tool relative to the tool guide when said tool is in a desired orientation relative to said tool guide, said first terminated passageway being in communication with said communication port of said tool guide when said tool is in said desired orientation.
 2. A drill string system of claim 1, wherein said alignment mechanism comprises an alignment key and a corresponding key slot.
 3. A drill string system of claim 2, wherein said alignment key comprises at least one biasable element.
 4. A drill string system of claim 2, wherein said alignment key comprises at least one biasable element wherein said alignment key extends longitudinally along said tool guide.
 5. A drill string system of claim 2, wherein said alignment key comprises at least one biasable element wherein said alignment key extends longitudinally along said tool guide wherein said alignment key is tapered at a lower longitudinal end thereof.
 6. A drill string system of claim 2, wherein said alignment key comprises at least one biasable element wherein said key slot extends longitudinally along said tool and is tapered at a lower longitudinal end thereof.
 7. A drill string system of claim 1, wherein said support comprises a fit ring connected to said tool guide via support legs extending longitudinally along said tool guide, said fit ring being fitted to said inner diameter of said drill string pipe.
 8. A drill string system of claim 1, wherein said drill string system comprises ring seals above and below said communication port on said tool guide.
 9. A drill string system of claim 8, wherein each ring seal is made of compressible material which permits said tool to slide within said landing shoe assembly.
 10. A drill string system of claim 1, wherein said at least one seal is provided on said outer surface of said tool.
 11. A drill string system of claim 1, wherein said support comprises at least one leg for spacing said tool guide in said drill string pipe.
 12. A drill string system of claim 11, wherein said support further comprises a fit ring connected to said at least one leg fitted to the inner surface of said drill string pipe.
 13. A drill string of claim 1, wherein said tool comprises at least one spacer at a lower end thereof for spacing the tool from the drill string pipe.
 14. A drill string of claim 13, wherein said at least one spacer comprises at least one fin extending generally radially from said tool.
 15. A drill string of claim 1, wherein said tool comprises a feature for abutting against said tool guide to limit downward movement of said tool in said drill string pipe.
 16. A drill string of claim 1, further comprising at least one seal for sealing said communication port in said tool guide and said first terminated passageway from fluid in said bore.
 17. A drill string of claim 1, further comprising at least one seal for sealing said communication port in said tool guide and said communication port in said drill pipe wall from fluid in said bore.
 18. A drill string system of claim 1, wherein said tool guide is tubular.
 19. A drill string system for performing measurement while drilling and logging while drilling operations for oil and gas drilling, said drill string system comprising: a drill string section having a bore defined by an inner length of surface of a pipe wall which also has an outer surface; a tool guide secured in said drill string section and a support for centering said tool guide in said bore; communication ports extending through said drill pipe wall from said outer pipe surface to said inner surface and through said support to an inner surface of said tool guide, said communication ports being in communication with one another; an elongate cylindrical tool disposed in said tool guide; a first pressure sensor within said tool to sense said drill string annular pressure; a second pressure sensor in said tool in communication with said drill string bore to sense said drill string bore pressure; a three-dimensional orientation sensor in said tool determining orientation of the tool; and a mechanical retention device connected to said tool guide for inhibiting rotation of said tool relative to the tool guide when said tool is in a desired orientation relative to said tool guide, said first terminated passageway being in communication with said communication port of said tool guide when said tool is in said desired orientation.
 20. A landing assembly for use in a drill string section, said landing sleeve assembly comprising: a tool guide for receiving an elongate cylindrical tool; a support for centering said tool guide in a bore of said drill string section; a communication port extending through said tool guide and said support for communication with a corresponding communication port in said drill string section and a pressure sensor in said tool when said landing assembly is placed in said drill string section; and a mechanical retention device connected to said tool guide and said support for inhibiting rotation of said tool relative to the tool guide when said tool is in a desired orientation relative to said tool guide. 